Having had every type of cabin offered, I have to state that there is absolutely nothing wrong with an Interior Cabin and unless I am given a complimentary upgrade, I see no reason any longer to pay the extra price. The balconies on Princess cruises are a joke as they are small and totally lack privacy. The suites are overpriced.
I sleep and shower in the cabin period. If I want to relax, I find a nice spot on the ship on deck or in one of many secluded comfy areas. Strange as it may sound, if the interior cabin is configured as two twins rather then pushed together, there is ample floor space inside the cabin. Would you rather spend more on a cabin and less on excursions?